diff --git a/libc/calls/cachestat.c b/libc/calls/cachestat.c
new file mode 100644
index 000000000..b24215b02
--- /dev/null
+++ b/libc/calls/cachestat.c
@@ -0,0 +1,47 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+
+#include "libc/calls/cachestat.h"
+#include "libc/intrin/strace.internal.h"
+
+int sys_cachestat(int, struct cachestat_range *, struct cachestat *, uint32_t);
+
+/**
+ * Query the page cache statistics of a file.
+ *
+ * @param fd The open file descriptor to retrieve statistics from.
+ * @param cstat_range The byte range in `fd` to query. When `len > 0`, the range
+ * is `[off..off + len]`. When `len` == 0, the range is from `off` to the end of
+ * `fd`.
+ * @param cstat The structure where page cache statistics are stored.
+ * @param flags Currently unused, and must be set to `0`.
+ * @return 0 on success, or -1 w/ errno.
+ * @raise EFAULT if `cstat_range` or `cstat` points to invalid memory
+ * @raise EINVAL if `flags` is nonzero
+ * @raise EBADF  if `fd` is negative or not open
+ * @raise EOPNOTSUPP if `fd` refers to a hugetlbfs file
+ * @raise ENOSYS if not Linux 6.5
+ */
+int cachestat(int fd, struct cachestat_range *cstat_range,
+              struct cachestat *cstat, uint32_t flags) {
+  int rc;
+  rc = sys_cachestat(fd, cstat_range, cstat, flags);
+  STRACE("cachestat(%d, %p, %p, %#x) → %d% m", fd, cstat_range, cstat, flags);
+  return rc;
+}
\ No newline at end of file
diff --git a/libc/calls/cachestat.h b/libc/calls/cachestat.h
new file mode 100644
index 000000000..1c3cd22f3
--- /dev/null
+++ b/libc/calls/cachestat.h
@@ -0,0 +1,34 @@
+#ifndef COSMOPOLITAN_LIBC_CALLS_CACHESTAT_H_
+#define COSMOPOLITAN_LIBC_CALLS_CACHESTAT_H_
+
+#if !(__ASSEMBLER__ + __LINKER__ + 0)
+COSMOPOLITAN_C_START_
+
+struct cachestat_range {
+  uint64_t off;
+  uint64_t len;
+};
+
+struct cachestat {
+  /** Number of cached pages. */
+  uint64_t nr_cache;
+  /** Number of dirty pages */
+  uint64_t nr_dirty;
+  /** Number of pages marked for writeback. */
+  uint64_t nr_writeback;
+  /** Number of pages evicted from the cache. */
+  uint64_t nr_evicted;
+  /**
+   * Number of recently evicted pages.
+   * A page is recently evicted if its last eviction was recent enough that its
+   * reentry to the cache would indicate that it is actively being used by the
+   * system, and that there is memory pressure on the system.
+   */
+  uint64_t nr_recently_evicted;
+};
+
+int cachestat(int, struct cachestat_range *, struct cachestat *, uint32_t);
+
+COSMOPOLITAN_C_END_
+#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
+#endif /* COSMOPOLITAN_LIBC_CALLS_LANDLOCK_H_ */
\ No newline at end of file